ML20134M663

Forwards Safety Evaluation Accepting Licensee Scope & Insp Methods Proposed for Insp of Core Spray Internal Piping During Fall 1996 Refueling Outage at Plant

ML20134M663
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	11/20/1996
From:	Craig Harbuck NRC (Affiliation Not Assigned)
To:	Reid D VERMONT YANKEE NUCLEAR POWER CORP.
Shared Package
ML20134M666	List: ML20134M663 ML20134N827
References
TAC-M96671, NUDOCS 9611250225
Download: ML20134M663 (4)

Text

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NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. - aaat l

i. November 20, 1996

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Mr. Donald A. Reid l Vice President, Operations j Vermont Yankee Nuclear Power Corporation i Ferry Road

[ Brattleboro, VT- 05301 i

SUBJECT:

REVIEW 0F CORE SPRAY SYSTEM PIPING COLLAR-TO-SHROUD WELD FLAW

EVALUATION AND CORE SPRAY SYSTEM INSPECTION PLAN AT VERMONT YANKEE NUCLEAR POWER STATION (TAC NOS. M96671 AND M96689)

Dear Mr. Reid:

During Vermont Yankee Nuclear Power Station's (Vermont Yankee's) fall 1996 refueling outage, Vermont Yankee Nuclear Power Corporation (VYNPC) identified  !

crack-like indications (or flaws) in collar-to-shroud welds IP8b and 3P8b j affecting two of the four piping collars on the core spray (CS) system  ;

downcomer piping internal to the reactor pressure vessel at Vermont Yankee. I The internal CS piping is attached to the core shroud at four locations where the CS piping penetrates the shroud by means of a piping sleeve or collar, which is external to the core shroud. One end of each collar is welded to the CS piping and one end is welded to the outside wall of the shroud. Thus, the welds containing the flaws, both collar-to-shroud welds, are not associated with the CS piping pressure boundary.

4 By letter dated October 9,1996, VYNPC submitted to the NRC its evaluation of the flaws'it had identified in the CS piping collar-to-shroud welds. The NRC staff has completed its review of VYNPC's submittal and concludes that the  ;

structural integrity of collar-to-shroud weld IP8b will be maintained during l the next- fuel cycle (cycle 19) under all design basis loading conditions. >

However, the submittal did not contain a sufficient basis for the NRC staff to conclude that collar-to-shroud weld 3P8b will maintain its structural integrity during the next fuel cycle under all design basis loading conditions. However, based on its review of the CS system piping analysis also contained in VYNPC's submittal, the NRC staff concurs with VYNPC's determination that the CS syctem piping internal to the reactor pressure vessel will be able to maintain its functionality even assuming that collar-to-shroud weld 3P8b loses its structural integrity. Therefore, Vermont Yankee can be operated through the end of fuel cycle 19 without repairing collar-to-shroud welds IP8b and 3P8b. The enclosed safety evaluation contains the basis for the NRC staff's conclusion. Based on this conclusion, the NAC staff informed VYNPC by telephone on October 11, 1996, that it did not consider the two CS piping collar-to-shroud weld flaws to be an issue for restart of Vermont Yankee from the fall 1996 refueling outage.

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D. Reid November 20, 1996 Operation of Vermont Yankee beyond fuel cycle 19 will depend on the satisfactory evaluation of the reinspection results or by implementing acceptable repairs during the next refueling outage. VYNPC is requested to submit its plans for reinspection and repair of the CS system piping internal to the reactor pressure vessel at least 3 months before the start of the next refueling outage.

By letter dated September 25, 1996, VYNPC informed the staff of its intention to modify its previous CS system inspection commitments associated with IE Bulletin (IEB) 80-13. " Cracking in Core Spray Spargers," dated May 12, 1980, during the fall 1996 refueling outage at Vermont Yankee. As described in the .

enclosed safety evaluation, the inspection methods proposed by VYNPC were to i

focus on areas of the CS piping which are more likely to experience intergranular-stress corrosion cracking. In addition, the proposed inspection methods for the CS internal downcomer piping are more stringent than those

recommended in IEB 80-13. Therefore, the NRC staff finds that the scope and 1 inspection methods proposed for the inspection of the CS internal piping during the fall 1996 refueling outage at Vermont Yankee are acceptable.

j Sincerely, l /s/

C. Craig Harbuck, Acting Senior-Project Manager Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-271

Enclosure:

Safety Evaluation I

cc w/ encl: See next page

) DISTRIBUTION:

Docket File JZwolinski OGC DTerao i

PUBLIC SBajwa ACRS JRajan PDI-1 Reading Slittle LDoerflein, RGN-I KWichman SVarga CHarbuck RHermann RWessman

! DOCUMENT NAME: G:\ VERMONT \VY96671.LTR *See previou's concurrence i To receive a copy of this document, indicate in the box: "C" - Copy without attachment / enclosure "E" - Copy with attachment / enclosure "N" - No copy l DFFICE PM:PDI 1 lE LA:PDI-1 l D:PDI 1 ,,s l BC:EMCB l BC:EMEB l NAME *CMarbuckerst *Stittle SBajwa /60 Q _ *KWichman *RWessman

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DATE 11/19/% 11/19/ % 11/ W % 11/19/ % 11/19/96

) Official Record Copy 1

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D. Reid Operation of Vermont Yankee beyond fuel cycle 19 will depend on the satisfactory evaluation of the reinspection results or by implementing acceptable repairs during the next refueling outage. VYNPC is requested to submit its plans for reinspection and repair of the CS system piping internal to the reactor pressure vessel at least 3 months before the start of the next refueling outage.

By letter dated September 25, 1996, VYNPC informed the staff of its intention to modify its previous CS system inspection commitments associated with IE Bulletin (IEB) 80-13, " Cracking in Core Spray Spargers," dated May 12, 1980, during the fall 1996 refueling outage at Vermont Yankee. As described in the enclosed safety evaluation, the inspection methods proposed by VYNPC were to focus on areas of the CS piping which are more likely to experience intergranular-stress corrosion cracking. In addition, the proposed inspection methods for the CS internal downcomer piping are more stringent than those recommended in IEB 80-13. Therefore, the NRC staff finds that the scope and inspection methods proposed for the inspection of the CS internal piping during the fall 1996 refueling outage at Vermont Yankee are acceptable.

Sincerely,

/ #

C. Craig Harbuck, Acting Senior Project Manager Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation Docket No. 50-271

Enclosure:

Safety Evaluation cc w/ encl: See next page

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D. Reid Vermont Yankee Nuclear Power Station Vermont Yankee Nuclear Power Corporation 1

'cc l l Regional Administrator, Region I G. Dana Bisbee, Esq. ,

U. S. Nuclear Regulatory Commission Deputy Attorney General l

475 Allendale Road 33 Capitol Street i King of Prussia, PA 19406 Concord, NH 03301-6937 5 i i

R. K. Gad, III Resident Inspector i j Ropes & Gray Vermont Yankee Nuclear Power Station  !

! One International Place .U.S. Nuclear Regulatory Commission  !

Boston, MA 02110-2624 P.O. Box 176

Vernon, VT 05354

! Mr. Richard P. Sedano, Commissioner

Vermont Department of Public Service Chief, Safety Unit 1 l 120 State Street, 3rd Floor Office of the Attorney General Montpelier, VT 05602 One Ashburton Place,19th Floor Boston, MA 02108 Public Service Board State of Vermont Mr. David Rodham, Director 120 State Street ATTN

James Muckerheide Montpelier, VT 05602 Massachusetts Civil Defense Agency 400 Worcester Rd.

Chairman, Board of Selectmen P.O. Box 1496 Town of Vernon' Framingham, MA 01701-0317 P.O. Box 116 Vernon, VT 05354-0116 Mr. Raymond N. McCandless Vermont Division of Occupational ,

Mr. Richard E. McCullough and Radiological Health l Operating Experience Coordinator Administration Building Vermont Yankee Nuclear Power Station Montpelier, VT 05602 P.O. Box 157 Governor Hunt Road Mr. J. J. Duffy Vernon, VT 05354 Licensing Engineer Vermont Yankee Nuclear Power Corporation 580 Main Street Bolton, MA 01740-1398 Mr. Robert J. Wanczyk, Plant Manager Vermont Yankee Nuclear Power Station i P.O. Box 157, Governor Hunt Road Vernon, VT 05354 Mr. Ross B. Barkhurst, President l Vermont Yankee Nuclear Power Corporation l Ferry Road l Brattleboro, VT 05301 l

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